Year	%
2000	30
2001	29.5
2002	28
2003	27.9
2004	26.4
2005	26.7
2006	27.3
2007	26.6
2008	27.5
2009	26.3
2010	25.8
2011	25.7
2012	23.2
2013	22.4
2014	24.3
2015	24.1
2016	23.5
2017	22.6
2018	22.2
2019	21.3